Sharif Digital Repository

A new switching method for the stabilisation of a one-dimensional capacitor array tank for the stepwise charging of a load capacitor is presented. In this method, the tank capacitor configuration is rearranged in a circular manner once the charging process of a load capacitor finishes and before the charging process of a new load capacitor begins. Unlike previously reported methods, this method does not require backward switching for the stabilisation of tank capacitor voltages. Hence, the proposed method reduces the number of charging process steps by a factor of up to 2 compared with the conventional method. Moreover, since the tank recycles its charge inherently, the capacitive load can... 

Waste water from ore plant layout central Alborz's coal has been investigated and analyzed. Studies showed that because of acidic character, the waste water contains heavy metals including Cu, Cr, Ba, Zn, V, Sr, Pb, Ni. Considering the importance of this topic for outgoing acidic waste waters which is hazardous for the environment, i.e. heavy metals, the same should not be transferred into the environment. Since their waste water is transferred into nearby agricultural ground, it was developed a method, so that waste water is primarily directed into a slug pond for sedimentation. In the second stage in another pond, the outflow of waste water was treated with chemicals. Also the pH was... 

The general goal of the facility layout problem is to arrange a given number of facilities to minimize the total cost associated with the known or projected interactions between them. One of the special classes of the facility layout problem is the Single Row Facility Layout Problem (SRFLP), which consists of finding an optimal linear placement of rectangular facilities with varying dimensions on a straight line. This paper first presents and proves a theorem to find the optimal solution of a special case of SRFLP. The results obtained by this theorem prove to be very useful in reducing the computational efforts when a new algorithm based on tabu search for the SRFLP is proposed in this... 

This article studies effects of webpage layout in an online retailer on buyer behavior towards new products and is a sequel to a study performed by authors in department stores. Webpage layout -in terms of parameters which influence buyer behavior- is formulated by two variables; pattern of prices and pattern of popularity. A novel method based on above-mentioned study, has been developed to measure these two factors, so that they can be compared against retailer sales statistics. Investigating this relationship helps both online retailers and marketing agents to better understand effect of webpage layout in promoting a newly developed product. Results show that correlation between price... 

This article studies effects of store layout in a department store on buyer behavior towards new products. Shelf layout -in terms of parameters which influence buyer behavior- is formulated by two variables; pattern of prices and pattern of popularity. A novel method based on previous works of authors has been developed to measure these two factors, so that they can be compared against shares of department sales statistics. Investigating this relationship helps both retailers and marketing agents to better understand effect of shelf layout in promoting a newly developed product. Results show that correlation between price difference and department share is strong. There is also a weaker... 

The fast growth of battery operated devices has made low power SRAM designs a necessity in recent years. Moreover, embedded SRAM units have become an important block in modern SoCs. The SRAM performance is limited by the cell stability during different operation. By adding extra transistor to the conventional 6T-cell, hold, read and write static noise margin (SNM) can be improved in the sub-threshold SRAM. In this paper we proposed a new 9T-cell SRAM that shows 80% and 50% improvement in read and write SNM respectively in comparison to the conventional 6T-cell SRAM. Using stack transistors in the leakage current path, the new structure shows lower bitline leakage assisting the sense... 

The purpose of this paper is to develop a global optimization model, simplification schemes, and a heuristic procedure for the design of a shortcut-enhanced unidirectional loop aisle-network with pick-up and drop-off stations. The objective is to minimize the total loaded and empty trip distances. This objective is the main determinant for the fleet size of the vehicles, which in turn is the driver of the total life-cycle cost of vehicle-based unit-load transport systems. The shortcut considerably reduces the length of the trips while maintaining the simplicity of the system. The global model solves simultaneously for the loop design, stations' locations and shortcut design. We then develop... 

The economic viability of industrial processes strongly depends on their safe and reliable operation. The method of inherent safe process design enables systematic consideration of safety measures in order to ensure process safe operation at the early stages of process design. The challenge is that the economic measures that are often considered for the design of industrial processes are often incommensurable with the safety measures. In the present research, a novel framework is proposed in which the safety criteria are quantified based on consequence modeling and aggregated with the economic performance using multi-objective optimization programming. The developed methodology was applied... 

An analytical method is presented to characterize stepwise adiabatic circuits (SACs). In this method, the SACs are modeled as a discrete time system. Unlike previous methods, the stability is verified for arbitrary load capacitor ratios. Moreover, this method presents analytical derivations to offer an area/energy efficient design methodology. MATLAB simulations, post-layout simulations in the CMOS 0.18 μm technology, silicon measurements, and measurements based on discrete components confirm the precision of the analytical derivations. Using the proposed design methodology, a capacitive tank has been designed which reduces the energy consumption by 20% while the total size of the tank... 

A new low-power switching procedure for stepwise capacitor chargers is presented. In this procedure, a novel displacement method is utilized to improve the speed by a factor of two while preserving energy efficiency. Moreover, the load capacitor retains its charge after the charging process finishes and permits the circuit charge another predischarged load capacitor without an efficiency degradation problem (instability). Also, the control circuit of the switching procedure is implemented using only flip-flops with no combinational logic, therefore, it systematically prevents glitch power dissipation and improves the efficiency. Analytical derivations are proposed to model the switching... 

Table forms are highly flexible and mobile form systems for beams and slabs. In this system, the components with standard dimensions are fabricated in production plants, transported to construction sites and assembled for final use. Then, based on the plan of the floor zone to be constructed and location of columns, beams, and openings, the assembled tables are placed next to each other and the gaps are covered to provide a perfect surface for concrete casting. However, since the tables are rectangular with standard dimensions, even the best layout does not guarantee the full coverage of the area with tables. The more the uncovered areas are, the more the extra formwork cost and required... 

A low-power high-speed two-stage dynamic comparator is presented. In this circuit, the voltage swing of the first stage of the comparator, pre-amplifier stage, is limited to Vdd/2 in order to reduce the first stage power consumption. Also, this voltage swing limitation provides a strong drive at the evaluation phase for the second stage to enhance the comparison speed. Analytical derivations along with post layout simulation results prove that the proposed method speeds up the conventional circuit by a factor of two in the same budget of power consumption and offset voltage. Furthermore, the proposed circuit offers a wide input common mode range as large as the supply voltage while employing... 

The Multi-Floor Layout Problem (MFLP) is the problem of finding the position of each department in a plant floor in a multi-floor building without any overlapping between departments in order to optimize a particular objective function, more commonly the sum of the material handling costs. In this paper, a special class of MFLP, called Uncertain Multi-Floor Discrete Layout Problem (UMFDLP), is defined. In this problem, a multi-floor building is considered in which an underground store is utilized to contain main storages, and different departments can be located in the other floors in potential pre-determined locations. Furthermore, all material flows are not constant. Moreover, the... 

Single floor facility layout problem (FLP) is related to finding the arrangement of a given number of departments within a facility; while in multi-floor FLP, the departments should be imbedded in some floors inside the facility. The significant influence of layout design on the effectiveness of any organization has turned FLP into an important issue. This paper presents a three- (two-) stage mathematical programming method to find competitive solutions for multi- (single-) floor problems. At the first stage, the departments are assigned to the floors through a mixed integer programming model (the single floor version does not require this stage). At the second stage, a nonlinear programming... 

In this manuscript a new phenomenon of adjacency and closeness rating is proposed for constructing the optimal facility layout design. In the proposed approach, the closeness rating is applied to every pair of neighboring departments in a range of their attached point up to a predefined distance between them. Also, while in the traditional approach the closeness rating is applied for determining either the proximity or farness of two departments, the proposed approach considers both the degree of closeness as the economical purposes, and farness as the safety purposes concurrently. A mathematical model is proposed for constructing the optimal layout design. For evaluating the efficiency and... 

Single-Row Facility Layout Problem (SRFLP) is a http://library.sharif.ir/web-manage/catalog/resource.do?method=edit&flowLastAction=view&id=447751special class of facilitylayout problems, consists of finding an optimal linear placement of rectangularfacilities with varying dimensions on a straight line. In this research, wefirst present a theorem to find the optimal solution of a special case of SRFLP.The results obtained by this theorem are very useful in reducing thecomputational efforts when, later on, a new algorithm based on tabu search ispresented for SRFLP. Computational results of the proposed algorithm onbenchmark problems show the efficiency of the algorithm compared to the... 

A novel method of transmitter (TX) leakage cancellation is presented to improve the dynamic range of the receiver for wideband code division multiple access applications. The large TX leakage is attenuated within the low noise amplifier (LNA) output using a feed-forward path without any LNA noise figure degradation. A prototype has been designed and laid out in 0.18 μm CMOS technology. It achieves a maximum TX rejection of 18.5 dB with only 5.2 mA current consumption from 1.8 V supply voltage. LNA P-1dBCP (1 dB gain compression point) against TX leakage improves by more than 10 dB. Post layout simulations verify these results. Proposed structure dispels the requirement of off-chip surface... 

We develop heuristic procedures for concurrent design of block layout, material flow network, and input and output stations. Unlike the common practice in the flexible bay structure layout design, our objective function includes both loaded and empty flow between pairs of I/O stations. This measure of effectiveness is the main determinant of the fleet size of the vehicles, which in turn is the major driver of the total investment and operational costs in vehicle-based material handling. Our work is the first to design flexible bay structure layouts for loop-based material flow patterns. We first develop heuristic algorithms to configure the layout on the foundations of a unidirectional loop...